A structural joint is formed between the upper frame rail, which bends downwardly to define a generally vertically extending portion, and a generally fore-and-aft extending lower frame rail that can increase bending resistance without sacrificing crash energy management of the horn section of the lower frame rail. The structural joint is reinforced with a crushable tubular reinforcement member formed in a clamshell configuration that includes a forwardly extending support arm positioned beneath the horn section to lower the center of gravity of a downwardly angled horn section to prevent premature bending thereof when encountering crash energy from a frontal impact. The horn section is formed in a pre-folded configuration to enhance the crash energy management of the horn section. The tubular reinforcement provides a double cell structural configuration adjacent the structural joint to provide a crushable structural joint that enables an effective management of crash energy.